Recently, with color photographic light-sensitive materials for photography, the attainment of high image quality has been particularly sought, and image quality capable of being appreciated even in the case of enlargement from a small format, for example, 110 size, has been desired. However, it has been strongly desired to achieve further make improvement in graininess and sharpness.
With respect to sharpness, a method for enhancement of the edge effect using DIR compounds, etc., is known, as represented by Japanese Patent Application (OPI) Nos. 36249/84 (U.S. Pat. 4,500,634) and 145135/79 (U.S. Pat. 4,248,962) (the term "OPI" as used herein refers to an "unexamined published application"), and a method for minimizing light scattering by reducing the thickness of layer coated. As described in Japanese Patent Application (OPI) No. 36249/84, greater effects can be achieved by the combination of these means.
In order to carry out the reduction of the layer thickness, there are known, for example, (1) a method of rendering a ballast group of a coupler small, (2) a method of decreasing the amount of an organic solvent having a high boiling point which is used as a solvent for a coupler, and (3) a method of polymerizing a coupler in order to provide color forming groups in high density, etc. However, the method (1) has a problem of diffusion-resistivity of the coupler. In method (2), it is difficult to excessively reduce the amount of organic solvent because of deposition of the couplers and an adverse affect on color forming property. Thus, remarkable reduction of the layer thickness can not be expected. Further, in the case of method (3) wherein polymerized couplers are used in the form of a latex or emulsified dispersion, when an amount of gelatin used is reduced in order to remarkably reduce the thickness of layer, strength of the layer lowers and it causes a defect in that the film is apt to be injured before exposure, and during and after processing.
Hydrophilic polymeric couplers are also known. For instance, polymeric couplers in which reactive couplers are bonded to a pre-synthesized polymer (for example, a homopolymer of acrylic acid, a homopolymer of p-aminostyrene, etc.) or a natural high molecular compound (for example, gelatin, etc.) are described, for example, in U.S. Pat. Nos. 2,698,797, 2,852,381, 2,852,383 and 2,870,712, Japanese Patent Publication Nos. 16932/60 and 3661/69, etc., and polymeric couplers obtained by copolymerization of a coupler synthesized in the form of an unsaturated ethylenic monomer with other polymerizable monomer are described, for example, in British Patents Nos. 880,206, 955,197, 967,503, 967,504, 995,363 and 1,104,658.
However, since the above described hydrophilic polymeric couplers have insufficient diffusion resistivity, color mixing between layers tends to occur and the couplers are discharged into a processing solution during processing. Due to such problems, they have not been practically utilized.
In order to solve such problems, there have been provided water-soluble polymer couplers having a group capable of crosslinking with gelatin through a hardener (for example, a hydrophilic polymeric coupler having a phenolic hydroxy group or an active methylene group) as described, for example, in U.S. Patents 4,207,109 and 4,215,195, Japanese Patent Application (OPI) Nos. 205735/82, 27139/83, and 28744/83, etc. However, since these polymers effect crosslinkage with gelatin through a hardener, the crosslinking rate is small and the efficiency of crosslinking of the coupler and gelatin is low due to reactions involving crosslinking couplers per se or gelatin per se through the hardeners. Accordingly, they are still insufficient in view of diffusion resistivity.